In order to repair Sana's and Nanaka's relationship, Syusuke and Syuri decide to go on a trip to a river that the five used to go to in their youth. Beforehand, Sana accidentally breaks Nanaka's mirror, and Nanaka is appreciative when Sana buys her a new one, but forlorn after learning that Sana bought one for Asami as well. After the group goes to the river, they swim at the spa, where Nanaka is embarrassed at her lackluster swimsuit. As Nanaka is going home with Sana and Aoi, she reveals she made cookies for the group, and the three eat them at Aoi's apartment. There, Sana gives Nanaka a pink stone he found near the river as a gift.
ぎくしゃくしている佐菜と菜々香の関係を気遣って、朱里と修輔が日曜日に幼馴染み5人で昔よく遊んだ川に出かける計画を立てた。しかし当日、佐菜から誘われたあさみも急遽参加することに。無邪気に川で遊んでいる皆に馴染めず、距離を置く菜々香。5年前にも、菜々香は初めての手作りクッキーを持って皆で同じ川に遊びに来ていた。その時のことを思い出し、クッキーを作ってきたのだが、カバンの中から出せずにいた。その帰り、水着で遊べるスパに行って・・・。
